1. Technical Field
The disclosure relates generally to metal-insulator-metal capacitors, and more particularly, to altering of a capacitive value of a MIM capacitor having a reactive layer therein.
2. Background Art
Passive elements such as metal-insulator-metal (MIM) capacitors, metal-insulator-semiconductor (MIS) capacitors or deep trench capacitors are widely used in integrated circuits for both digital and analog mixed signal technologies. For example, back-end-of-line (BEOL) MIM capacitors and front-end-of-line (FEOL) planar MIM or MIS or deep trench capacitors are commonly used. The critical integration factor for these passive elements is their capacitance value tolerances. For example, precision capacitors have tolerances of +/−10 to 15%.
Conventionally, passive element tolerance is controlled during fabrication by a number of approaches. One past approach includes trimming the capacitors to adjust their capacitance tolerance using, e.g., lasers or etching processes. Laser trimming of capacitors, however, is rarely practiced because it damages structure surrounding the capacitors, and creates yield issues. Another current approach includes using electronic fuses (e-fuses) to fuse in or out smaller capacitors that adjust the capacitance tolerance of the overall capacitor based on electrical test data. Unfortunately, trimming capacitors using e-fuses add what are effectively dangling radio frequency (rf) antennas, and also require the use of complicated e-fuse circuits. Furthermore, the space required for the e-fuses oftentimes results in wasted space due to the extra area required. For example, for a MIM capacitor requiring 100 picoFarads (pF), a 90 pF MIM would be placed with two additional 1 Opf MIMs, which could be wired in parallel to increase the capacitance. If one or both of these 10 pF capacitors were not needed (i.e., the intended-to-be 90 pF MIM actually resulted in the desired 100 pF MIM), then space occupied by the 10 pF capacitors and the associated e-fuses and circuitry are wasted.